Session bootstrap swallowed configure/retrieval errors and surfaced only the generic BOOTSTRAP_FAILURE_MESSAGE, so an operator could not tell why a session "didn't start" — e.g. `tht search pack` failing because the DWH/vector host is unresolvable behind a dropped VPN. Log the underlying error to the backend console; the client-facing message stays generic. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>